| AVS 54th International Symposium | |
| Electronic Materials and Processing | Wednesday Sessions |
| Session EM-WeM |
| Session: | Contacts, Interfaces and Defects in Semiconductors |
| Presenter: | R.S. Okojie, NASA Glenn Research Center |
| Correspondent: | Click to Email |
The utilization of Silicon Carbide (SiC) semiconductor-based microsystems targeted for extreme applications (i.e., high temperature, high power, extreme vibration, and aggressive chemical environments) has largely been hindered by intrinsic material defects and the reliability issues that are associated with the stability of the contact metallization.1 In this talk, the research efforts at NASA Glenn to resolve the reliability problems of the contact metallization will be presented, which includes the in-depth reliability studies to identify the multilayer metallization that provides stable long-term performance of ohmic contact to SiC. The observation of process-induced stacking faults (SFs) has also been determined to present a reliability problem to 4H-SiC polytype devices. The formation of single and multiple stacking faults that sometimes give rise to 3C-SiC was observed in several doped n-type 4H-SiC epilayer following thermal oxidation. Transmission electron microscopy following oxidation revealed double stacking faults and bands of 3C-SiC in the 4H-SiC epilayer. Depth-resolved cathodoluminescence spectroscopy at 25 oC based on low energy-excited electron nanoscale luminescence revealed a spectral peak at 2.5 eV photon energy that was not present in the sample prior to oxidation. This is in addition to the 3.22 eV photon energy peak corresponding to 4H-SiC.2 The polytypic transformation is attributed to the motion of Shockley partial dislocations on the (0001) slip planes.3 Auger electron spectroscopy, Scanning Electron Microscopy, Transmission electron microscopy, and current-voltage measurements that were used to develop an in-depth knowledge of these failure mechanisms will be discussed.
1P. G. Neudeck, R. S. Okojie, Liang-Yu Chen, Proceedings of the IEEE, Vol: 90 , Issue: 6 , pp.1065 . 1076. 2004
2R.S. Okojie, D. Lukco, L. J. Brillson S. Tumakha, G. Jessen, M. Xhang and P. Pirouz,. Appl. Phys. Lett. 79, 3056 (2001).
3Robert. S. Okojie and Ming Zhang, in Silicon Carbide 2004-Materials Processing and Devices, edited by Michael Dudley, Perena Gouma, Tsunenobu Kimoto, Philip G. Neudeck, and Stephen E. Saddow (Mater. Res. Soc. Symp. Proc. 815, Warrendale, PA , 2004).